Activation of the Ras protein contributes to the development of a wide variety of human cancers. In addition to its growth-promoting properties Ras has recently been identified as a potent inhibitor of anoikis, or suspension-induced cell death. Anoikis represents a physiologically appropriate response of epithelial cells to loss of adhesion. Circumventing this response is a prerequisite for metastasis, one of the most lethal aspects of cancer. The work proposed in this fellowship utilizes a novel model for anoikis studies, the Rat Intestinal Epithelial-1 (RIE-1) cell line, to identify signaling properties of Ras that block anoikis. Unlike what has been proposed with other epithelial cell lines, preliminary data suggest that multiple signaling properties of Ras promote anoikis resistance of RIE-1 cells. The specific aims of this research are to determine (i) what effector(s) of Ras contributes to anoikis resistance, (ii) the role of a Ras/Epidermal Growth Factor Receptor autocrine loop in mediating anoikis resistance, (iii) if Ras-mediated regulation of the Jun terminal Kinase or Nuclear Factor kappa B activity attenuates anoikis and (iv) if loss of mutant Ras expression or inactivation of Ras effectors can restore anoikis sensitivity to the human colon carcinoma cell line DLD-1.